I disagree that they all play the same. They play similarly. Hopefully more differences come into play later on in the development cycle in the game, however some of the differences do actually change how I play the game.

The Iridium for example. They get multiple trade buildings that also increase influence. I find I am far less likely to build up manufacturing when playing them. I tend to focus on influence and money with only a few dedicated planets for manufacturing. I rush build and buy ships and tech from others far more often.

The Altarians do not get the good terriforming techs so I know from the get go that I will need to maximize my planets or they will lose ground at end game.

The Iconians get free upgrades on their starbases so it is faster to swarm starbases with them....

If you are truly not adjusting how you play when you change factions... you are probably missing out on some of the more interesting ways to play.

Personally my favorite faction so far is the Iridium as I much prefer the diplomatic and economic victory over the crushing war victory.

My custom human race. They are based mostly on research, spending is locked 60% Research 40% Manufacturing. Plus they get a research trait bonus.

I play peaceful and nice investing to develop my planets while I colonize more and more to the farthest possible any direction.By the time I meet other factions I have already a large empire no military power or tech but I play it nice on them and if they dare to colonize a planet in my area they doom themselves... culture flip is only matter of time (for most races anyway).

After I got all the important techs for planet development /culture and economy I go to engineering and finally military techs. I'm alrady far ahead from other factions in research and economy. Building a super advanced large fleet ensures my domination always... never lost a game.

I usually play straight Terrans in space games for bunches of reasons. In GC3 standard races, I like the Krynn for some reason, though. An emphasis on growth and culture works for me. I also expect them to develop as Espionage develops. All that is likely to change as things balance and re-balance.

In the end, my favorite is the one I make up for my self. Not only is it fun for flavor, but I love setting my own traits and tech tree. Right now, I am Nobody of Nowhere representing Everybody Else. The traits are similar to the Krynn, but different enough to seem to matter. The tech tree is standard until I learn the tech trees better. I have Iconian style ships in some reverse color scheme that makes them all shiny multicolor like dragonflies. (Very psychedelic in the Battle Viewer.) The Ship Designator prefix comes from the Department of Misinformation and where races like the Terrans have "T.A.S.", we have the text "not a". Therefore, when you inspect one of our ships, all you know is it's "not a Constructor MK4-21", or "not a Cruiser M22-1", etc. All of these slightly-out-of-format labels look bizarre and amusing in the various dialogue boxes. That is why it is my favorite faction. The short description I have so far is "Anonymous, but deadly."

i usually play a custom synthetic race with the AOE techs for starbases added ini go malevelent for the homeworld manufacturing bonus then get my homeworld up to where i can pump out a colony ship every turn and complete the assembly project every other turn.....

i use the colony ships to scout out planets and colonize pushing my range further and further

*as i side note i reduce ship range down to -0.20 from the like 2.8 modifier it normally gets